Obd2 VR6 No Closed Loop? (Update P4, advice please)

[VRTrickster 0]

I just tested the lambda signal wire whilst running and cleaned the ecu pins. I was getting 0.6v constant when first started. When it warmed up a bit I got a reading of 0.0v to 0.2v fluctuating. So I should get a signal on vagcom if all the wiring is ok, which tested all good when I checked last week. :?

 

Im not getting any lambda readings what so ever. Would I see readings when cold on vagcom?

 

Correction, I've just tested it again at the signal wire whilst running. From start it was 0.6, then after it had warmed right up, I tested it again and got 0.02v to 0.03v fluctuating. I also pulled the fuel reg hose and blocked it off and not much happened, maybe went up to 0.05v/0.06v.

 

This would indicate the lambda is dead? I feel really stupid now as I just purchased a second hand ecu today for £45 quid. I'm just throwing money away left right and centre here! :mad2:

[VRTrickster 0]

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[VRTrickster 0]

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[VRTrickster 0]

Ive still got this problem and its driving me insane!

 

Ive been chatting to Vince and he is pretty stumped too. I've now replaced the injectors with recons and its still exactly the same. The cars is not going into closed loop and Im still getting the lambda short to ground code.

 

Heres a vagcom log file to show what the lambda readings are up to.

 

Also Im still getting 34 mpg on motorway runs. :?

 

Anyone got any ideas, cos Ive pretty much run out? The ecu has also been swapped. New testing signal wires from the ecu to lambda sensor.

[toyotec 0]

Hi I am new on this forum, but not new to ECUs and calibration. I own a Mk3 VR6 with your ECU i.e. M 3.8.1. and understand a bit of the logic behind this Euro coded Bosch PCM. I am assuming this vehicle had recalibration done to suit the hardware?

Lambda correction of 10 - 20% was this a negative value? The maximum lambda correction for is +/- 25% to target ?=1and the maximum adaptation value for addaption, multiplicative or additional (idle loads), is +/- 30%. Lambda correction occurs as kev says from a calibratable 70 deg C and lambda voltage between ~ 0.1-0.8v is dictated by the lambda control function and bias. Lambda correction is switched off on a decel, cat heating and dewpoint, diagnostic sensor plausablity fault or on a load threshold or by codeword.

I suspect there may be an issue with the calibration if all has been checked.

[VRTrickster 0]

Hi I am new on this forum, but not new to ECUs and calibration. I own a Mk3 VR6 with your ECU i.e. M 3.8.1. and understand a bit of the logic behind this Euro coded Bosch PCM. I am assuming this vehicle had recalibration done to suit the hardware?

Lambda correction of 10 - 20% was this a negative value? The maximum lambda correction for is +/- 25% to target ?=1and the maximum adaptation value for addaption, multiplicative or additional (idle loads), is +/- 30%. Lambda correction occurs as kev says from a calibratable 70 deg C and lambda voltage between ~ 0.1-0.8v is dictated by the lambda control function and bias. Lambda correction is switched off on a decel, cat heating and dewpoint, diagnostic sensor plausablity fault or on a load threshold or by codeword.

I suspect there may be an issue with the calibration if all has been checked.

 

Doe's the not need to be in closed loop for it to start calibrating? The only code I get is lambda short to ground. The car seems to be running lean on throttle and perhaps rich and being compensated on idle? But it really has lost me now. I think I'm just going to have to pass it on to someone else to diagnose, at my expense! How do I check calibration? :?

[Supercharged 2]

Surely short to grd just points to a wiring issue - have you checked the car side of the loom as Corrado's are notorious for breaking very close to the lambda connector due to heat and engine mount failure...

[VRTrickster 0]

All the wiring was tested good. I then rigged up some other test signal wires and it was still the same.

[toyotec 0]

Hi I am new on this forum, but not new to ECUs and calibration. I own a Mk3 VR6 with your ECU i.e. M 3.8.1. and understand a bit of the logic behind this Euro coded Bosch PCM. I am assuming this vehicle had recalibration done to suit the hardware?

Lambda correction of 10 - 20% was this a negative value? The maximum lambda correction for is +/- 25% to target ?=1and the maximum adaptation value for addaption, multiplicative or additional (idle loads), is +/- 30%. Lambda correction occurs as kev says from a calibratable 70 deg C and lambda voltage between ~ 0.1-0.8v is dictated by the lambda control function and bias. Lambda correction is switched off on a decel, cat heating and dewpoint, diagnostic sensor plausablity fault or on a load threshold or by codeword.

I suspect there may be an issue with the calibration if all has been checked.

 

Doe's the not need to be in closed loop for it to start calibrating? The only code I get is lambda short to ground. The car seems to be running lean on throttle and perhaps rich and being compensated on idle? But it really has lost me now. I think I'm just going to have to pass it on to someone else to diagnose, at my expense! How do I check calibration? :?

 

You mean correcting? If so yes. Feed back from the only HEGO sensor is sent to the ecus lambda controller where it targets 0.450v or Lambda 1. If it were "OBD2" compatible the you also have a rear HEGO to monitor cat condition and add trim. Euro coded PCMs do not have this function.

As already suggested. Check the lambda fault first. The calibration or "map" suggestion is really the last thing and maybe something out of your scope.

Lambda short to ground though? Do you mean "Oxygen (Lambda) Sensor Heating Circuit: Short to Ground"? Is that what you saw on the diagnostic tool?

[VRTrickster 0]

Lambda short to ground though? Do you mean "Oxygen (Lambda) Sensor Heating Circuit: Short to Ground"? Is that what you saw on the diagnostic tool?

 

Yes this is the only code it is throwing on vag com (00525 Oxygen sensor short to ground). I get lambda voltage readings on there though which are no higher than .500v, but it drops to .000v at idle. On part throttle though, it seems to give readings of around .350v to .500v.

[toyotec 0]

Replace lambda sensor. It would seem the heater on the sensor is faulty, causing high current draw from the heater circuit causing the fault to be triggered. The sensor should be replaced with an OE bosch unit. 0.5v to 0.0v to 0.5v is abnormal. The std settings in that cal suggest the system must wobble through 0.45v from ~0.1v to 0.7v then back to 0.1v or lean, rich, lean...

[VRTrickster 0]

Replace lambda sensor. It would seem the heater on the sensor is faulty, causing high current draw from the heater circuit causing the fault to be triggered. The sensor should be replaced with an OE bosch unit. 0.5v to 0.0v to 0.5v is abnormal. The std settings in that cal suggest the system must wobble through 0.45v from ~0.1v to 0.7v then back to 0.1v or lean, rich, lean...

 

This is the forth lambda sensor. First was an after market ebay job which had the heater element short to ground code your talking about. The car actually run better with this one fitted. The second was a geniune Bosch sensor. The car run like a pig and was giving the lambda sensor short to ground and no other code. I took it back off and noticed I had put a big dent in it, so I thought that must be the problem. I am now on the third new Bosch sensor, same code!

 

I dont think its the sensor or the wiring maybe? I was starting to think maybe a slight leak in the downpipe? You cant really see anything because of all the heat shield covering.

 

I'm really annoyed as I have had to give up now as its driving me mad! I usually do everything on my car and can't really afford to give it to someone else at the moment. At least its drivable and not drinking lots of fuel. My main concern is the MOT is due in Jan.

 

Thanks for any advice you can give.

[toyotec 0]

Replace lambda sensor. It would seem the heater on the sensor is faulty, causing high current draw from the heater circuit causing the fault to be triggered. The sensor should be replaced with an OE bosch unit. 0.5v to 0.0v to 0.5v is abnormal. The std settings in that cal suggest the system must wobble through 0.45v from ~0.1v to 0.7v then back to 0.1v or lean, rich, lean...

 

This is the forth lambda sensor. First was an after market ebay job which had the heater element short to ground code your talking about. The car actually run better with this one fitted. The second was a geniune Bosch sensor. The car run like a pig and was giving the lambda sensor short to ground and no other code. I took it back off and noticed I had put a big dent in it, so I thought that must be the problem. I am now on the third new Bosch sensor, same code!

 

I dont think its the sensor or the wiring maybe? I was starting to think maybe a slight leak in the downpipe? You cant really see anything because of all the heat shield covering.

 

I'm really annoyed as I have had to give up now as its driving me mad! I usually do everything on my car and can't really afford to give it to someone else at the moment. At least its drivable and not drinking lots of fuel. My main concern is the MOT is due in Jan.

 

Thanks for any advice you can give.

 

I just re-read this thread and saw that you had changed the sensor several times so apologies and you also tested the sensor wires. I am assuming here that the current ECU is remapped? You said you have another ECU have you tried this?

Also when did you first notice the problem?

[VRTrickster 0]

The car is not remapped. I'm running on the swapped ecu at the moment, so that would rule out the ecu. I've recently installed recon injectors also to see if that was causing the problem.

 

When did it all start, well quite a while ago now. The car has always had a bit of an idle issue. Sometimes I would pull up and it would be lumpy, then other times idle fine. I'm wondering if its something that's became progressively worse over time?

[VRTrickster 0]

Parts replaced/swapped so far:

 

Inlet manifold gaskets

Exhaust downpipe, checked cat

Recon injectors

ECU

Crank sensor

Cam sensor

Cheap denso plugs, may try some NGKs?

Lambda sensor x3 Bosch items (Wiring has been checked)

Fitted separate lambda signal test wires

Checked for vac leaks

Compression test (All six at 180psi ish)

 

Things I was thinking of swapping:

 

Coil pack

Throttle body

Denso to NGK plugs

Evap purge valve

 

Fault codes:

 

(00525 Lambda sensor short to ground)

 

Symptoms:

 

Rough idle pulsing, maybe a slight misfire on idle. Fine on the motorway 34mpg. When sat at the lights you can see the mpg going down. It's not going into closed loop. The car just passed on emissions for the MOT. It had high CO, and the rest normal compared to the last test.

 

Any other advice would be great. I'm out of work at the moment but as soon as I can afford it I'll have to bite the bullet and take it to Vince at Stealth.

Edited February 24, 2011 by VRTrickster

[Kevin Bacon 5]

Sorry to hear about your work situation :(

 

I take it all 3 sensors came up with "Short to ground" ?

 

So in VCDS, you're driving along and you can see some activity in "Lambda active" and some % adjustments, but when the idle map kicks in, the Lambda activity is null and adjustment is 0%? And I take it the fault codes are clear when driving, but as soon as the engine idles, the short to ground error appears?

 

Do you have a wideband lambda display? If yes, what is the AFR at idle?

 

Very strange. I think it's probably time to fold the towel up neatly and put it back in the airing cupboard mate. This is going to need more measuring kit and in-depth diagnosis, i.e. Vince!

[VRTrickster 0]

Sorry to hear about your work situation :(

 

I take it all 3 sensors came up with "Short to ground" ?

 

So in VCDS, you're driving along and you can see some activity in "Lambda active" and some % adjustments, but when the idle map kicks in, the Lambda activity is null and adjustment is 0%? And I take it the fault codes are clear when driving, but as soon as the engine idles, the short to ground error appears?

 

Do you have a wideband lambda display? If yes, what is the AFR at idle?

 

Very strange. I think it's probably time to fold the towel up neatly and put it back in the airing cupboard mate. This is going to need more measuring kit and in-depth diagnosis, i.e. Vince!

 

Yeah it's looking that way mate. The problem is I've been using the car as a van for some agency work I did for a couple of weeks and it's been really getting to me. One because of the way it's running and two because of how dirty its been getting! I feel as though the condition of it is deteriorating rapidly.

 

I see lambda activity on throttle, nothing above 0.500v. Then at idle it sort of drops down to zero. I don't really get any adaptation happening, maybe the odd occasion you might get some percentages happening, but only for a second or two a on the lambda %. I do see a lambda value of -14.1% but I'm not sure what it is, maybe LTFT?

I'm not sure if the code disappears after it's displayed? I think it stays stored?

 

Thanks for any advice you can give kev. Perhaps anything else I could check on vag com that I don't know about, like fuel trims? I know taking it to Vince is looking like my only option now, but I need funds for that, oh well.

Edited February 24, 2011 by VRTrickster

[toyotec 0]

A lambda value of -15% suggests the "fr" value or regulation factor from the lambda controller is removing 15% of fuel at that time to allow the lambda sensor to correct to 0.455v or lambda 1.

If there are no air leaks ACF ( purge) or diagnostics going on your fr value should be +/- 5%.

The upper and lower limts for fr are calibrated to +/-25% and the upper and lower limits of both idle and parlt load adaptive lambda are +/- 30%.

However if you change the ECU for another and have the same issue then the problem is not the ECU it is the hardware.